1. Field of the Invention
The present application relates generally to an improved data processing system and method. More specifically, the present application is directed to improving system utilization through dedicated uncapped partitions.
2. Background of the Invention
Virtualization of computing resources is important in current computer environments. International Business Machine's POWER™ hypervisor, which is part of the firmware in Power 5™ systems, allows the virtualization of physical processors. Hypervisor is a virtual manager that partitions a system into multiple virtual machines and manages the system's resources across the virtual machines. These partitions can use whole physical processors or a fractional part of a whole physical processor. Each partition is assigned virtual processors that get mapped to a whole or a fractional part of physical processors by the Hypervisor. In case of fractional processor entitlement, physical processors are time-sliced across the virtual processors. In such an environment, fractional processor allocations enable a greater number of partitions than the number of available physical processors in the system. In addition, each of these partitions may have an arbitrary number of virtual processors in each partition or virtual machine. This configuration allows an opportunity for any partition to use all the available processors at any time if entitlement is defined as uncapped and the physical processors are idle in the system. Partition entitlement is the amount of time a partition is guaranteed to get processor time within a dispatch wheel time (time slice). Within the partition, virtual processors run to limits of partitioned entitlement before virtual processors are time-sliced or virtual processors running in a partition cede their cycles as a result of lack of work to do, that is, other partitions are idle. The “uncapped partition entitlement” allows the partition to use more resources than what the entitlement limit is set. The partition entitlement of a partition is evenly distributed amongst the online virtual processors so that the number of online virtual processors impacts the length of each virtual processor's dispatch cycle.
In addition to entitlement, partitions are divided into two types of partitions, namely dedicated logical partitions and shared logical partitions. Shared logical partition resources are managed as part of a shared pool and dedicated logical partition resources are dedicated to a given partition meaning the resources are not part of a pool where multiple partitions can share the resources. If the dedicated partition is configured to donate cycles, then dedicated partition processor cycles are given to shared partitions. However, the dedicated partition processor's cycles is not part of the shared pool per se. While dedicated logical partition resources are allowed to be given to shared logical partitions if the dedicated logical partition resources are idle and not used by the dedicated logical partitions, the reverse is not true. That is, if the resources in shared pool are not used by shared partitions, the resources are wasted and never allowed to be given to dedicated partitions. This is due to the fact that a dedicated logical partition is not allowed to use more resources than the dedicated logical partition is configured for. Therefore, even with virtualization there are situations where resources go unused. By introducing various types of virtual machines or partitions, the system is tailored to suit different types of situations. However there is still room for improving system utilization by allowing complete flexibility.